Equivalent to useCount() == 0 (must be SharedPtr.WeakType).
Method exists only if SharedPtr is isWeak
{ SharedPtr!long x = SharedPtr!long.make(123); auto wx = x.weak; //weak pointer assert(wx.expired == false); x = null; assert(wx.expired == true); }
See Implementation
Equivalent to useCount() == 0 (must be SharedPtr.WeakType).
Method exists only if SharedPtr is isWeak